1. Field of the Invention
The present invention relates to communication systems and more particularly to a communication system capable of transmitting data messages comprising a plurality of languages.
2. Background Discussion
Communication systems in general and paging systems in particular- using transmitted call signals have attained widespread use for calling selected receivers to transmit information from a base station transmitter to the receivers. Modern paging receivers have achieved multifunction capability through the use of microcomputers which allow the paging receiver to respond to information having various combinations of tone, tone and voice, or data messages. The information is transmitted using any number of paging coding schemes and message formats. The paging coding schemes preferably are of the multi-character word length type, where the character may be a binary digit or the like. Prior art paging systems have been able to transmit and receive data message information in only one language such as English. The languages referred to in the present invention have as a common denominator symbols and words arranged in a traditional semantic relationship. The widespread use of paging systems now require that data messages comprised of different languages be transmitted to a paging receiver for receiving and displaying the symbols of the languages to the paging receiver user. These languages include alphabetic languages such as English, French, German, or the like as well as ideographic languages such as Japanese, Chinese, or the like.
In the operation of such paging receivers, important factors involved in their successful operation is the portability of the receiver, the limited energy available for the receiver, the amount of memory available for the paging receiver's microcomputer, the limited availability of the radio spectrum, the fast response time required in today's active society, and the number of paging receivers included in the paging system. In such paging receivers, in order that the drain on the battery may be minimized, the paging receiver is systematically turned off and turned on to maximize the length of time energy is available from the batteries. The limited energy in which the paging receiver must operate limits the memory and minimizes the electronic circuitry such as the display in the paging receiver. The fast response time and the number of paging receivers requires the data messages to be compressed. In the case of sending data messages including a plurality of languages, the characters for each language are compressed to a common set of characters before transmission. Within these constraints, a paging receiver must commercially operate.
The known prior art consists of existing printing systems and CRT terminals adopted to print text material in different languages. For instance, U.S. Pat. No. 3,996,584 shows a display for a CRT terminal which uses two character generators for displaying different groups of characters. Another example of the prior art is U.S. Pat. No. 4,122,533 which shows a character generating system for a photocomposition machine for displaying alphanumeric symbols on a CRT for any language selected from a group of languages. These prior art systems, however, did not operate under the constraints required of a paging receiver. These constraints are the limited power available to the paging receiver, the demand on the radio spectrum, the limited memory, the portability, the data compression, and the real time response required for a paging receiver in a paging system.